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Old 15th November 2006, 07:11 AM   #1
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Post Searching Sound Valves M40 Monoblocks schematic

I own a pair of used Sound Valves M40 Monoblocks, I am trying to make some modification on it, Please help me to get the schematic of the amplifier, Your helps are greatly appreciated. Many many thanks!

My email address:
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Old 15th November 2006, 04:23 PM   #2
kevinkr is offline kevinkr  United States
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I googled Sound Valves and Sound Values (the name of the original company.) I reviewed their VTP-101i pre-amp more than 10 years ago..

Unfortunately they seem to be out of business at this point. I found their old web address and unfortunately it now belongs to a cyber squatter..

The M40 is very similar to the Dynaco MKIV IIRC, but doesn't use a 7199 but something like a 6AN8 instead? (Again IIRC)

I have seen and heard the M40, but my recollection is more than a little fuzzy since it was more than 10yrs ago.

Try triode connecting the EL34 output tubes, remove the UL taps coming from the output transformers from pin 4 of the EL34's and connect a 220 - 1K resistor from pin 3 to 4. (screen grid to plate) Be sure to insulate the disconnected tap wires well as there is full B+ plus rather a lot of AC audio voltage present when operating.

Upgrade the coupling caps as there are much better ones out there now.

Here is a link to a review of the pre-amplifier (not my review) with possibly useful historical contact info (ignore the email and website addresses obviously):

Sorry, wish I could be of more help.
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
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Old 25th January 2008, 01:32 AM   #3
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These sound best stock. They did a good job on the circuit and they did not approve of wiring for triode. I do have the original schematic if you still need it.
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